1. Field of the Invention
The present invention relates to a data update method, a data update system, and a terminal used by the data update system.
2. Description of the Related Art
Data update for a database (hereinafter abbreviated to DB where proper) requires resources (computer resources) such as central processing units (CPU's) and memories. A process of updating a large amount of data becomes a load of a database of a terminal having limited resources such as an embedded system.
A database in an embedded system is not managed heretofore by middleware such as a database management system, but an application in the embedded system creates processes originally.
However, original data management by the application in the embedded system is becoming difficult to have higher performance and reliability requested to the embedded system, because of large capacity and versatility of data to be processed, caused by the recent advance in storage technologies and higher functionality of the embedded system. Further, speed of product developments is becoming more important, because of intensified competition in embedded system markets.
Under these circumstances, recognition prevails in which productivity of software developments is enhanced by separating applications and data management not by mounting the database of a terminal in an application in the embedded system, but by adopting a high performance relational database (RDB) operating in a computer having abundant resources such as a center.
In order to operate a high performance RDB in an embedded system having a performance lower than that of the center, it is necessary to reduce processing. One example of reducing processing is to utilize log data of an update command. For example, according to the techniques disclosed in JP-A-2004-145827, when update is performed in one apparatus, the update command is recorded as log, and when update is performed in another apparatus, the log is also utilized.